May 1, 2015 - 3:00pm - 4:00pm
Research in the Costanzo lab focuses upon the exploitation of simple and efficient chemistry to prepare novel materials. In particular, Diels-Alder (DA) chemistry is becoming increasing popular due to its simplicity and efficiency. It also imparts a thermo-responsive aspect which can result in the preparation of dynamic materials. First, thermally responsive surfaces have been developed towards the goal of creating self-pressurizing capillaries. By controlling the functionality, the surface energy can be manipulated to be either hydrophilic or hydrophobic. The ability to switch between these energetic states would allow for the expulsion of fluid from a capillary. Second, a soybean based coating with thermally responsive DA linkages has been prepared following an automotive 2-component formulation. The resulting coatings displayed the capability to be healed following physical deformation by a thermal stimulus, and such a material has significant potential for end users. Various curing agents were employed, and resulted in variation of scratch resistance and re-healablity. Different thermally responsive soybean resins were synthesized to have varying amounts reversible and nonreversible linkages when incorporated into the coating. Additionally, different isocyanates were added at differing ratios of NCO:OH in search of the optimum coating. It was found through the analysis of rehealabilty, hardness, gloss, and adhesion that the optimal combination was an acetylated resin (no irreversible crosslinks) with 54% reversible DA linkages at an NCO:OH ratio of 5:1 using isophorone diiscocyanate. Materials were evaluated via differential scanning calorimetry (DSC), scratch resistance, Koenig hardness, gloss measurements, and topographical analysis. Finally, DA chemistry was incorporated within various polymer matrices to integrate dynamic topology changes. DA functional groups were incorporated via initiators, crosslinkers and an inimer to integrate DA linkages. Upon the application of a thermal stimulus, the retro-DA was induced and topological changes were induced upon the polymer backbone.